Solar water heater

Jeremy, Reeves and Andy from Puget Sound Solar have been here for the last three days, installing our solar water heater. They’ve done a great job working within the constraints of our existing system: the cabinet the water heater lives in appears to have been built around the water heater, so there was no way to get it out, and there’s not much room above it for extra plumbing. Jeremy removed several panels of the cabinet in order to get access to the water tank, since it had to come out to have a heat exchange wand installed in it. We saved some money by already having a relatively new 65-gallon electric water heater, so we didn’t have to buy a whole new tank, just a solar heating wand.

I’ve taken some photos, and added a bunch of explanatory labels to this one. Here’s the summary of how it works: the solar collectors on the roof and the heat exchange wand in the storage tank are connected by a closed plumbing loop in which an antifreeze solution can be circulated. When there’s sunlight and the temperature of the fluid is higher than the temperature in the storage tank, the circulation pump turns on, sending heat from the collector down into the tank by means of the wand inserted in the tank. If the water in the storage tank hits 210 degrees, the pump shuts off in order to avoid boiling the water and triggering the pressure valve in the storage tank. (If the heat exchange fluid boils, there’s a pressure valve on the roof it will escape through, at which point we’ll need to call for service.) When there’s no sunlight, the electric heater kicks in and maintains the temperature in the storage tank at around 125 degrees. Since the water in the tank can get a lot hotter than you’d want to be exposed to, there’s an anti-scalding valve connected just after the outflow from the tank. It takes hot water from the tank and cold water from the main and mixes them to a more appropriate temperature, adjustable between 100 and 145 degrees, before sending it out to the house plumbing.

It’s a pretty keen system, and during the months when there’s anything resembling sunlight, it should save us a bunch on our electric bill. Jeremy, who has a similar setup, says that he’s able to turn the electric heater off entirely for something like April through September.

I can’t wait for there to be some sun, so I can watch the gauges change.

30 thoughts on “Solar water heater”

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Hey hey that’s pretty neat. Apparently the solar collector is capable of boiling sixty-five gallons of water so you could probably rig that antifreeze pump around some sort of heat engine IF ONLY SUCH TECHNOLOGY EXISTED.

Around five grand, but there are some good tax incentives in place right now, so I’m not sure how much it works out to in the end. And that price included a fair amount of labor for running new plumbing and electrical. I don’t have the numbers handy, but given how much it could potentially reduce our electric bill, I think it stands a good chance of paying for itself before it’s out of warranty, let alone at end of life.

Interesting. Is that a regular old GE water heater then? Does it have a longer-than-normal lifetime? (By normal, I’ve heard 7-15 years on water heaters with tanks. Hence, some people advocate tankless.)

It’s just a regular water heater, yeah. It has a 9 year warranty, and we’ve had it for 3 years, so when it wears out in 6-12 years, we can unscrew the solar wand from it and have the tank replaced. I’m not sure what the limiting factor on the lifetime of a water heater is, though. If it’s the heating elements, then we may be prolonging the useful life of the tank, too.

It’s probably worth noting that now that it’s sunny, I don’t think the system is working quite right. It may be that the pump is under-powered, but for whatever reason, the heat exchange liquid doesn’t seem to be circulating. I’ve got a call in to Jeremy to see what he thinks.

Jeremy came out and flushed and refilled the loop, and it seems to be working again. He thinks that there must have been a bubble preventing the pump from circulating the liquid. We’re going to keep an eye on it for a while and make sure that it stays working, and he’s going to double-check that the pump has enough power for the friction in the loop (which it seems to, so my guess was probably wrong).

Josh
Have you found out if your system can boil water? Can you tell where you would find out about the incentives for installing solar systems I am assuming the power Co. or is there a Gov office just for this type of thing?

How did the system perform over the winter? How much of your hot water was it able to produce? Did you consider the other tube system from Thermomax, their Mazdon system? I looked up the comparison sheets on SRCC (Solar Rating Certification Corporation) website at http://www.solar-rating.org/ratings/ratings.htm and observed the Mazdon had better performance at producing high changes in temp, which may be critical for winter performance.

Doug:

For incentives on these and other systems, take a look at the Database of State Incentives for Renewables & Efficiency. Search Google for ‘dsireusa’ or just go to their website athttp://www.dsireusa.org/

Winter in Seattle means almost no direct sunlight, so the performance wasn’t great. On days when there was any sun at all, it did contribute, but for the most part there wasn’t enough sun for it to do anything. I won’t have actual numbers until this coming winter, as I didn’t have any kind of data logger set up until a month or two ago.

Solar water heaters are very much a regional item. I also live in Seattle and there’s no way I’d get one to work.

Tankless water heater are a great source of fast heat. Not every jurisdiction allows them, so check your city ordinances to make sure it’s ok. In my experience they’ve been much more reliable than a usual tank water heater and over time the tankless variety will save you money.

Sunmaxx, Apricus, and BTF Solar are three more evacuated tube collector makers and/or distributers in addition to Thermomax. As of right now, Sunmaxx seems to be the most attractively priced, if one looks at the SRCC performance ratings in comparison to their prices (e.g. ~$1000 for 30 tubes and ~$750 for 20 tubes when on sale).

Great system.
If you want to prolong the life of your hotwater heater then it is as simple as replacing the safricial anode. Replacing your anode every 5 or 6 years can upto double the life of your tank.We have been replacing our anode on our solar unit for 17 years now and it is still going.It is a Rheem tank.
You can get some great info on anode replacement at http://www.calltheplumber.net.au

Yes! Keeping in mind the drastic environmental changes and rising fuel prices going Solar is one option open to all at minimal investments. The Solar Water heating systems are so easy to install and most of them come in a Do-it Yourself kit, With the technological advancement the once heavy, bulky hard to move panels are now available widely in light weight easy to carry by one personal only packages. The advancement in technology is not only limited to light weight, but for those concern about the aesthetics of the panels, the good news is that the panels are now available with a variety of trim colors to choose from and can be easily matched to your roof. Saving about $25.oo on ones electricity bill every month on a residence of 4. We all use hot water, as one of our basic needs and what can be a better way, than helping our environment, saving our resources and ourself’s some money other than by investing in a Solar Water Heating System.
There are a couple useful websites I’m aware off, that I would like to share with you
1. http://www.dsireusa.org – is a comprehensive source of information on state, local
, utility ans federal incentives that promote renewable engery ans energy efficieny.
2. http://www.powerpartnerssolar.com – one of the many manufacturers of certified Solar Water Heating Systems available. One place I saw the light weight panels and trim color options I was mentioning earlier.
Lastly, the local utilites in some areas also provide additional rebates and incentives for adding a Solar Water Heating Sytem to your exisitng water tank.
Keep the look out on. Feel Good and save- money for you, environment for us.

These systems are getting more and more popular.
We are getting loads of inquiry’s from people converting their whole house green. Finding a good supplier in Australia is hard. I am looking at importing from overseas.

We have had a number of customers combine this type of solar water heater with a tankless water heater to make sure that they never have a shortage of hot water when they really need it. It seems to be a perfect match for saving energy and making sure you have enough hot water for your needs.